Telematics services are those services that are provided by a remotely located call center to a vehicle and/or to an operator of the vehicle via an automatic and/or on-demand communications link connecting the call center to the vehicle. The use of telematics services by vehicle operators has grown steadily since such services first became available. Some of the more common telematics services include, but are not limited to, turn-by-turn navigation guidance, assistance during times of emergency, cellular telephone services, and the remote monitoring of a vehicle's maintenance requirements.
A vehicle that is capable of providing its driver with such telematics services typically includes an embedded telematics unit that is integrated into the vehicle and that is configured to communicate with the remotely located call center. The remotely located call center is configured, equipped and staffed to provide the above services (as well as others) to a vehicle operator through communications with the vehicle and/or the driver via the embedded telematics unit.
In a typical example, the driver will press a button or other control device in the vehicle requesting assistance from the call center. The button press will cause the embedded telematics unit to initiate a cellular telephone call to the call center. After an initial exchange of data between the telematics unit and the call center, voice communications will be established to permit an advisor at the call center to speak with the driver. To facilitate such voice communications, a directional wideband microphone having a wideband frequency response is included in the vehicle and is communicatively connected to the telematics unit.
The location where the directional wideband microphone is positioned in the vehicle has evolved over the years. Initially, the directional wideband microphone was mounted to the rear view mirror. In some instances, it was mounted to the bottom of the mirror and in other instances, it was mounted to the top. While both locations were acceptable, they each had drawbacks. The position beneath the mirror placed the directional wideband microphone close to the vehicle's stereo speakers and the vehicle's heating, ventilation, and air conditioning (HVAC) ducts, each of which emitted sound when utilized. The position above the mirror resulted in the directional wideband microphone's acoustic axis being directed up into the vehicle's headliner which is an inherently sound deadening material. Accordingly, both locations could potentially interfere with the directional wideband microphone's receptivity to sound energy, and could, as a result, diminish the microphone's ability to detect the vehicle occupant's voice.
Because of these drawbacks, designers began to explore positioning the directional wideband microphone at locations other than in or on the mirror. For example, directional wideband microphones were mounted in overhead consoles and in A-pillars. By positioning the directional wideband microphones in these locations, designers achieved better results, i.e., the directional wideband microphones experienced less interference from the radio and the HVAC ducts and therefore better maintained their wideband receptivity.
Because of the popularity of the above described telematics services, aftermarket telematics units are beginning to enter the market place. Such aftermarket telematics units make it possible for drivers of vehicles that lack an embedded telematics unit to, nevertheless, receive some or all of the telematics services available to drivers having vehicles with embedded telematics units. These aftermarket telematics units are self contained units that have many or all of the components of an embedded telematics unit.
Many of these aftermarket telematics units are in the form of a rear view mirror and are intended to replace the rear view mirror that comes with the vehicle. These aftermarket telematics units also include a directional wideband microphone to facilitate voice communications between the driver of the vehicle and the call center. The directional wideband microphones mounted in such aftermarket telematics units may therefore encounter the same sources of noise and interference that previously lead designers to move the directional wideband microphones out of the mirrors to other parts of the vehicle interior.
Another consideration is the effect that the packaging/mounting of the directional wideband microphone will have on the microphone's wideband receptivity. It has been observed that the greater the number of attachment points or the greater the area of attachment between a wideband microphone and the body to which it is mounted, the more vibrations from vehicle and vehicle systems will interfere with the directional wideband microphone's wideband receptivity. Because existing directional wideband microphone assemblies are packaged in a rigid housing made of hard plastic, and because the housings are relatively large, simply inserting the microphone assembly into the aftermarket telematics unit may result in large areas of contact between rigid, vibration transmitting surfaces.